Immunosuppressive effects of recombinant interferon-alpha during long-term treatment of cancer patients.

Interferons (IFN) are known to modulate immune responses in an either stimulatory or inhibitory manner. Most of the knowledge about immunomodulatory activities of IFN comes from investigations of IFN effects on cells in vitro. This study examines the influence which long-term treatment with recombinant interferon-alpha 2 exerts on immune functions in cancer patients. Serial in vitro immune function studies of peripheral blood mononuclear cells were done to determine parameters of B-cell and T-cell functions as well as natural killer (NK)-cell activity. The authors detected profound suppression of in vitro immunoglobulin synthesis and lymphocyte proliferation as well as depression of NK-cell activity during IFN treatment. All suppressed immune functions normalized on discontinuation of IFN therapy. The authors conclude from these observations that, apart from their beneficial effects, IFN produce substantial immunosuppression.